BOSTON (AP) -- After honoring the victims and the survivors of the Boston Marathon bombings, the Red Sox kept on with their best start in 11 years by beating the Kansas City Royals 4-3 Saturday as David Ortiz played his first game since last summer and Daniel Nava hit a three-run homer in the eighth inning.

The Red Sox wore white home jerseys with ''Boston'' on the front instead of the customary ''Red Sox.'' The shirts will be auctioned off for a fund to support victims of the bombing.

Kansas City players and staff wore a ''B Strong'' patch on the front of their jerseys. Neil Diamond sang Red Sox favorite ''Sweet Caroline'' before the bottom of the eighth.

The 37-year-old Ortiz injured his right Achilles tendon running the bases on July 17 and appeared just once in Boston's final 72 games, against the Royals on Aug. 24.

Ortiz was bothered by inflammation in both heels during spring training and didn't play in any exhibition games. He was 2 for 4 in his return, tying the score 1-all with a sixth-inning RBI single off James Shields.

Following the emotional pregame ceremony, the Red Sox won their sixth straight games - four since Monday's bombings at the marathon finish line.

Clay Buchholz (4-0) allowed eight hits in eight innings, struck out six and walked one. Andrew Bailey allowed Lorenzo Cain's leadoff homer over the Green Monster in the ninth, his fourth hit of the game, then got his third save when Alex Gordon hit a game-ending groundout with two on.

Shields gave up one run and four hits in six innings with eight strikeouts and three walks.

Buchholz extended his scoreless streak to 22 innings before Cain doubled in the fifth and scored on Jeff Francoeur's single.

Cain doubled leading off the seventh and scored on Salvador Perez's two-out RBI triple for a 2-1 lead. But Jonny Gomes doubled against Tim Collins starting the eighth and Dustin Pedroia walked. After Ortiz grounded into a double play, Kelvin Herrera (1-2) walked Mike Napoli on four pitches and Nava homered to right.

NOTES: Cain is 11 for his last 16. ... Shields entered just 2-9 with a 5.86 ERA in his career in Fenway Park. ... Boston OF Shane Victorino left the game with lower back tightness. ... Boston's starters have allowed three or fewer runs in all 16 games this season.